/**

 * Copyright (c) 2006-2015 Apple Inc. All rights reserved.

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 **/

#include "base64.h"

#include <stdlib.h>

#include <string.h>

// base64 tables

static char basis_64[] =

    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

static signed char index_64[128] =

{

    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,

    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,

    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,62, -1,-1,-1,63,

    52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1,-1,-1,-1,

    -1, 0, 1, 2,  3, 4, 5, 6,  7, 8, 9,10, 11,12,13,14,

    15,16,17,18, 19,20,21,22, 23,24,25,-1, -1,-1,-1,-1,

    -1,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,

    41,42,43,44, 45,46,47,48, 49,50,51,-1, -1,-1,-1,-1

};

#define CHAR64(c)  (((c) < 0 || (c) > 127) ? -1 : index_64[(c)])

// base64_encode    :    base64 encode

//

// value            :    data to encode

// vlen             :    length of data

// (result)         :    new char[] - c-str of result

char *base64_encode(const unsigned char *value, size_t vlen)

{

    char *result = (char *)malloc((vlen * 4) / 3 + 5);

    char *out = result;

    while (vlen >= 3)

    {

        *out++ = basis_64[value[0] >> 2];

        *out++ = basis_64[((value[0] << 4) & 0x30) | (value[1] >> 4)];

        *out++ = basis_64[((value[1] << 2) & 0x3C) | (value[2] >> 6)];

        *out++ = basis_64[value[2] & 0x3F];

        value += 3;

        vlen -= 3;

    }

    if (vlen > 0)

    {

        *out++ = basis_64[value[0] >> 2];

        unsigned char oval = (value[0] << 4) & 0x30;

        if (vlen > 1) oval |= value[1] >> 4;

        *out++ = basis_64[oval];

        *out++ = (vlen < 2) ? '=' : basis_64[(value[1] << 2) & 0x3C];

        *out++ = '=';

    }

    *out = '\0';

    return result;

}

// base64_decode    :    base64 decode

//

// value            :    c-str to decode

// rlen             :    length of decoded result

// (result)         :    new unsigned char[] - decoded result

unsigned char *base64_decode(const char *value, size_t *rlen)

{

    *rlen = 0;

    int c1, c2, c3, c4;

    size_t vlen = strlen(value);

    unsigned char *result =(unsigned char *)malloc((vlen * 3) / 4 + 1);

    unsigned char *out = result;

    while (1) {

        if (value[0]==0) {

            return result;

        }

        c1 = value[0];

        if (CHAR64(c1) == -1) {

            goto base64_decode_error;;

        }

        c2 = value[1];

        if (CHAR64(c2) == -1) {

            goto base64_decode_error;;

        }

        c3 = value[2];

        if ((c3 != '=') && (CHAR64(c3) == -1)) {

            goto base64_decode_error;;

        }

        c4 = value[3];

        if ((c4 != '=') && (CHAR64(c4) == -1)) {

            goto base64_decode_error;;

        }

        value += 4;

        *out++ = (CHAR64(c1) << 2) | (CHAR64(c2) >> 4);

        *rlen += 1;

        if (c3 != '=') {

            *out++ = ((CHAR64(c2) << 4) & 0xf0) | (CHAR64(c3) >> 2);

            *rlen += 1;

            if (c4 != '=') {

                *out++ = ((CHAR64(c3) << 6) & 0xc0) | CHAR64(c4);

                *rlen += 1;

            }

        }

    }

base64_decode_error:

    *result = 0;

    *rlen = 0;

    return result;

}